(1) Field of the Invention
The present invention pertains to beam mode discharge fluorescent lamps and more particularly to an arrangement for configuring the electrodes within a beam mode discharge fluorescent lamp.
(2) Description of the Prior Art
U.S. patent application Ser. No. 219,564, filed on Dec. 23, 1980, for a "Beam Mode Fluorescent Lamp", and assigned to the same assignee as the present invention, discloses a particular embodiment of a fluorescent lamp suitable for replacing the conventional incandescent bulb. Although incandescent lamps are inexpensive and convenient to use, they are considerably less efficient than fluorescent lamps.
In the above mentioned patent application, a single anode and cathode configuration is shown. This configuration requires three power terminals connecting the cathode and anode to the two power sources. In an alternate configuration in this application, a four terminal and two power source configuration is shown in which a heating filament is provided to heat the cathode for the production of electrons.
It is desirable to minimize the number of power sources and power connections from the power source to the anode and cathode of the fluorescent lamp. Thereby, the cost of the resulting lamp is less. In addition, such a scheme provides for simpler assembly during manufacture.
Further, grid shaped anodes are taught by the above mentioned application. These anodes are relatively expensive to manufacture and were believed to be necessary to accelerate the primary electrons in the discharge space.
As pointed out in the above mentioned patent application, the placement and location of the anode and cathode is of critical importance.